This proposal is a continuation of a project started three years ago, directed to the effects of exercise on genetic hypertensive rats. During the forthcoming year we intend to investigate the reflex changes that occur with lower body negative pressure and/or with neck suction in trained and nontrained SHR groups that are unanesthetized as well as anesthetized. Related studies are to be conducted with sympathectomized, borderline hypertensive (DOCA pellets) and diabetic groups. Our current investigations on wall/lumen ratios are to be continued; however, we intend to examine carotid baroreceptors to determine if anatomical changes are associated with the attenuated reflex responses of trained animals. By using the doppler flow procedures of Brody, we plan to measure mesenteric and renal flow during exercise in nontrained and trained animals. This procedure will also be employed during the lower body negative and suction tests. Since our previous studies have shown that chronic exercise, when between 50-60% VO2max, will significantly lower resting blood pressure, we will train animals for 20 weeks and then detrain them for 10 additional weeks. After the detraining period, the animals will be subjected to tests which will evaluate reflex and functional responses.